1. Field of the Invention
This invention relates to a process for producing capacitors, and is more particularly concerned with a process in which individual layer capacitors are cut from a mother capacitor which has been wound upon a drum.
2. Description of the Prior Art
A process for producing an electrical stack or layer capacitor includes winding, on a drum, synthetic layers, as dielectrics, and having metallizations applied thereto as coatings, to form a mother capacitor. The individual capacitors are separated from the master capacitor by sawing, whereby because of the development of heat during the sawing process, the capacitor foils, which are in a stretched state and capable of contraction, contract in the region of the cut edges thereby causing the coatings in this region to be broken and form islands. The islands, due to oxidation, are insulating islands.
Capacitors produced by the foregoing type of process are well known in the art. In order to achieve a clean contraction of the stretched synthetic material layers, which contraction is necessary for a good insulation of the cut edges, the cutting speed and the execution of the saw are selected in such a fashion that the cut edges are just sufficiently warmed for a contraction. With certain materials, such as polyethylene terephthalate for example, this leads to a melting of the synthetic material layer edges resulting from the saw cut. In this way, the cut edge of the sawed capacitor becomes smeared; the melting synthetic material is carried along by the cutting blade in the operating direction thereof and a burr or fin is formed in the region of the cut surfaces, which burr borders on the actual capacitor and protrudes beyond the actual capacitor in the operating direction of the saw blade. On the other hand, the saw blade gums up after a very short time and must be changed.